Thank you for your answer. I found the github action file, which helped me understand how PyMC is tested. I will see if I can investigate the seeding issue when running all the test suite at once: it only takes 1/2 hour on my laptop and I like to make sure that I am not missing anything.
I also found out that test_printing.py is referenced nowhere in the github action file, and hence probably never tested. Is this intentional? Or would you like me to add it somewhere?